There is no portable device that allows measurement and recording of rail vertical movement during full service of a train or locomotive. Currently, the only way to measure this distance between the tracks is measured is with a mechanical measuring device without the ability to data log, or detect approaching train, or send the data to an external device. A need exists for a portable, light-weight, electronic device that mounts easily to the web of the rail and the base on the ground and data logs the information that includes maximum/minimum vertical rail displacement.